J. Chem. Soc., Perkin Trans. 1, 1999, 1759–1763 1759

One-pot stereoselective synthesis of perfluoroalkylated (E)-allylicalcohols mediated by Ti(OPri)4 and Ph3P

1

Yanchang Shen,* Yuming Zhang and Yuefen Zhou

Shanghai Institute of Organic Chemistry, Academia Sinica, 354 Fenglin Lu, Shanghai 200032,China

Received 23rd November 1999, Accepted 20th April 1999

Synthesis of perfluoroalkylated (E)-allylic alcohols by the ‘one-pot’ reaction of equimolar amounts of aldehyde,3-bromo-1,1,1-trifluoroacetone (or α-bromoalkyl perfluoroalkyl ketone), triphenylphosphine and titanium()isopropoxide is described. The reductive olefination products were obtained in good yields exclusively in E-form.Thus this methodology provides a very convenient synthesis of perfluoroalkylated (E)-allylic alcohols and thewidespread use of these allylic alcohols is quite important in organic synthesis. They are interesting fluorinatedbuilding blocks, not easily available by existing synthetic methods. A possible mechanism for the explanation offormation of reductive olefinic products and the stereochemical results is proposed.

IntroductionTitanium-containing compounds have emerged as syntheticallyuseful reagents in organic synthesis in recent years.2 Amongthem, titanium() isopropoxide occupies an importantposition, particularly in asymmetric synthesis. The well knownSharpless asymmetric epoxidation is carried out by usingtitanium() isopropoxide as a catalyst.3 It was combined withBINOL as a catalyst in the Mukaiyama aldol condensation 4a

and used as a Lewis acid for catalyzed cyclopropanation ofallylic alcohols.4b A number of catalytic and stoichiometrictitanium-mediated hydrosilylations of carbonyl compoundshave been reported applying to the reduction of esters,5

lactones 6 and to the conversion of amides to aldehydes.7

Allylic alcohols are employed as useful building blocks inmany synthetic applications, particularly in the synthesis ofbiologically active compounds 8 and may undergo a lot ofuseful organic transformations.9 A number of methods forthe preparation of allylic alcohols are known,10 but multiplesteps are necessary or else the starting materials are notcommercially available. Recently a new stereoselective methodfor the preparation of allylic alcohols by using nickel-catalyzedalkylative cyclization of ynals or coupling of aldehydes, alkynesand organozincs has been reported.11 However, the synthesisof perfluoroalkylated allylic alcohols 12a–e and difluorospecies 12e–h is still limited. The Grignard reaction betweenvinyl bromides and trifluoroacetaldehyde gave α-trifluoro-methylated allylic alcohols, but ultrasonic irradiation wasfound to be necessary.12a The reduction of α-hydroxy alkynes,which were prepared by the reaction of trifluoroacetaldehydewith alkynyllithium compounds, gave α-trifluoromethylatedallylic alchhols.12b Another route to α-trifluoromethylatedallylic alcohols was by using a Wittig-type reaction.12c,d Thusthe literature methods for the preparation of the title com-pounds mainly lack convenience and the starting materials hadto be prepared in advance.

One-pot synthesis has attracted much interest in recent yearsbecause it provides a simple and efficient entry to compoundsby including two or more transformations in a single operationto increase the complexity of a product starting from com-mercially available, relatively simple precursors.13 In our labor-atory, ‘one-pot’ carbon–carbon double-bond formation hasbeen attained between α-bromo carboxylic derivatives (esters,amides and nitriles) and aldehydes in the presence of n-Bu3-

P(As) and catalyst (Pd,14,15 Zn,16–19 Cd 20). α,β-Unsaturatedesters,14,16,17,20 amides 15,18 and nitriles 19 were formed. The geom-etry of the newly formed double bond in the product wasexclusively or predominantly E in esters and amides. This reac-tion greatly simplifies the traditional Wittig reaction into astereospecific alkenylation methodology and compresses thethree steps of a Wittig reaction into a one-step, one-pot syn-thesis.14,21 Therefore efforts to develop an effective ‘one-pot’method for the preparation of allylic alcohols, especially fluorospecies, have attracted much attention. Herein we report a novelreductive olefination mediated by Ti(OPri)4 and Ph3P and itsapplication to the ‘one-pot’ stereoselective synthesis ofperfluoroalkylated (E)-allylic alcohols.

Results and discussionThe reaction is carried out neat. On heating equivalent amountsof aldehyde 1, 3-bromo-1,1,1-trifluoroacetone 2, triphenyl-phosphine and titanium() isopropoxide at 80 8C for 24 h, afterwork-up, reductive olefinic products 3 were obtained in goodyields exclusively as the E-form (Scheme 1). The results aresummarized in Table 1.

As an extension of this method a number of substrates 4

Table 1 Preparation of perfluoroalkylated allylic alcohols a mediatedby Ti(OPri)4 and Ph3P

Compound R Yield (%) b

3a3b3c3d3e3f3g3h3i3j3k3l

C6H5

4-CH3C6H4

4-FC6H4

4-ClC6H4

4-CH3OC6H4

4-NO2C6H4

3-BrC6H4

3-ClC6H4

2-BrC6H4

E-C6H5CH]]CH2,4-Cl2C6H3

Piperonyl

909987775455717895816451

a All reactions were carried out neat at 80 8C for 24 h, using 1.0 equiv.each of Ti(OPri)4, Ph3P, 3-bromo-1,1,1-trifluoroacetone 2 and aldehyde1. b Isolated yields. All new compounds were characterized by micro-analyses, IR, NMR and mass spectroscopy.

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1760 J. Chem. Soc., Perkin Trans. 1, 1999, 1759–1763

Table 2 Substituted allylic alcohols prepared a

Reaction

Compound R R 1 Rf Temp. (T/8C) Time (t/h) Yield (%) b

5a5b5c5d5e5f5g5h5i5j5k5l

C6H5

3-ClC6H4

3-ClC6H4

4-CH3OC6H4

2-BrC6H4

4-CH3OC6H4

E-C6H4CH]]CH2,4-Cl2C6H3

C6H5

4-FC6H4

2-BrC6H4

4-CH3OC6H4

CH3

CH3

n-Prn-PrCH3

CH3

CH3

CH3

CH3

CH3

CH3

CH3

CF3

CF3

CF3

CF3

C2F5

C2F5

C2F5

C2F5

n-C3F7

n-C3F7

n-C3F7

n-C3F7

10010010010090909090

110110110110

222222222424242422222222

726090426791997987806578

a All reactions were carried out neat using 1.0 equiv. each of Ti(OPri)4, Ph3P, bromoalkyl perfluoroalkylketone 4 and aldehyde 1. b Isolated yields. Allnew compounds were characterized by microanalyses, IR, NMR and mass spectroscopy. The configurations of the products were determined byNOESY spectra showing that the CH(OH)(Rf) group is cis (Z) with respect to CH]]C. Therefore the double bond in compounds 5 is in the E-configuration.

were investigated. All reactions proceed well giving substitutedallylic alcohols 5 solely as the E-isomers (Scheme 2).

The results are summarized in Table 2. Unfortunately,attempts to extend this reaction to aliphatic aldehydes failed. Aresinous product was obtained, and purified product was hardto isolate.

In order to elucidate the reaction mechanism we did the fol-lowing experiments: 1. 3-Bromo-1,1,1-trifluoroacetone 2 wasshown to react with titanium() isopropoxide by independentexperiment. When 2 reacted with titanium() isopropoxide at80 8C for 2 h, tetraalkoxide 6 was isolated and characterized,22

and it further reacted with 4-chlorobenzaldehyde in the pres-ence of Ph3P to give the desired product 3d. Acetone was alsoisolated and characterized (see Scheme 3).

2. In the absence of titanium() isopropoxide, no olefin-ation occurred under the same conditions. Thus, a possiblemechanism involving triphenylphosphine attack on 3-bromo-1,1,1-trifluoroacetone 2 to give the enolate, followed by aldolcondensation, transferring the Ph3P

+Br onto the hydroxylic

oxygen, followed by elimination of HBr from cation 7, and aMeerwein–Ponndorf–Verley 1,2-reduction of the enone prod-uct, seems to be discounted. If the above mentioned mechanismis correct, the olefination product should be obtained in theabsence of titanium() isopropoxide.

3. (Trifluoroacetylmethylene)triphenylphosphorane (Wittigolefination ylide) did not react with aldehydes in the presence of

Scheme 1

Ph3P/Ti(O-i-Pr)4

3

C C

H

CH

R

OH

HCF3

RCHO + BrCH2 C CF3

O

21

Scheme 2

Ph3P/Ti(O-i-Pr)4

5

C C

R1

CH

R

OH

HRf

RCHO + BrCHR1 C Rf

O

41

Scheme 3

+OTi(O-i-Pr)3

CHCF3 CH2Br

O

CH3CCH3BrCH2CCF3 + Ti(O-i-Pr)4

O80 °C/2h

2 6

titanium() isopropoxide to give allylic alcohols, but insteadthe aldehyde was reduced by titanium() isopropoxide toafford the corresponding alcohol (57%) (Scheme 4). Thus amechanism via Wittig ylide seems to be unreasonable.

4. Attempts to carry out the reductive olefination by use offluorine-free α-bromo ketone BrCH2C(O)Ph 11 instead of 2were unsuccessful. There is a competing reaction of titanium()isopropoxide between 2 (or 11) and an aldehyde. In the fluorine-containing case, the reaction of titanium() isopropoxide with2 takes place smoothly since 2 is more reactive than an aldehydedue to the strong electron-withdrawing effect of the CF3 group,while in the fluorine-free case the aldehyde is more reactive thanbromo ketone 11. Thus the reductive olefination failed when 11was used as substrate.

5. Other halophilic reagents, such as n-Bu3P (89% yield of3a), n-Bu3As (92% yield of 3a) and n-Bu3Sb (68% yield of 3a),can also be used in this reaction instead of Ph3P by combin-ation with Ti(OPri)4.

Thus, the tentative hypothesis shown in Schemes 5, 6, and 7appears to be consistent with the information currentlyavailable.

The reaction is postulated to be initiated by a Meerwein–Ponndorf–Verley-like reduction of 3-bromo-1,1,1-trifluoro-acetone 2 with titanium() isopropoxide 23 to give 6 (Scheme 5).A halophilic reaction occurred between intermediate 6 and

Scheme 4

Ph3P CHC(O)CF3 + 2,4-Cl2C6H3CHO

2,4-Cl2C6H3CH CHCHCF32,4-Cl2C6H3CH2OH

OH

Ti(O-i-Pr)4 Ti(O-i-Pr)4

Scheme 5

C

O

CH2Br

Ti

O

CH

CH3

CH3CF3

BrCH2CCF3 + Ti(O-i-Pr)4

O

OTi(O-i-Pr)3

CHCF3 CH2Br

O

CH3CCH3

2

6

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J. Chem. Soc., Perkin Trans. 1, 1999, 1759–1763 1761

triphenylphosphine, forming ion-pair 7 and 8 (Scheme 6) whichwas analogous to that reported in the literature.24 It might bestabilized by the strongly electron-withdrawing trifluoromethylgroup.

Subsequently the active species 7 and 8 reacted with aldehydethereby forming a six-membered intermediate 9. After elimin-ation of triphenylphosphine oxide and HBr the intermediate 10was formed, which on hydrolysis gave the product 3 (Scheme 7).

Intermediate 9 is similar to that reported in the literature 25 inwhich it was shown to be present by an HBr-cleavage experi-ment. It is different to the Mitsunobu reaction 26 since nobromoalkane was obtained.

The intermediate 9, in which the CHCF3[OTi(OPri)3] groupis located anti with respect to the R group, is a favorable con-figuration energetically and, after elimination of triphenyl-phosphine oxide and HBr, leads to the above E-isomer. Thusthe stereochemical results can be rationalized.

The most intriguing aspect is that the sequence of reactionsproceeds via Meerwein–Ponndorf–Verley reduction of BrCH2-COCF3 first, and then the product reacts with Ph3P since thebromofluoro compound is more reactive than aldehydes.

These studies provide a very convenient synthesis ofperfluoroalkylated (E)-allylic alcohols efficiently and stereo-selectively, and the widespread use of these allylic alcohols isquite important in organic synthesis. They are interestingfluorinated building blocks, not easily available by existingsynthetic methods, and would be expected to be useful inter-mediates for the synthesis of fluorine-containing biologicallyactive compounds.

ExperimentalBps and mps are uncorrected. The IR spectra of liquid prod-ucts as films and of solid products as KCl disks were taken on aDigilab FTS-20E spectrometer. 1H NMR spectra were recordedon a Bruker AM-300 (300 MHz) spectrometer (δ-values in ppmfrom tetramethylsilane, in CDCl3; J -values are given in Hz). 19FNMR spectra were taken on a Varian EM-360 (60 MHz) spec-trometer (δ in ppm from external trifluoroacetic acid, in CDCl3,positive for upfield shifts). Mass spectra were measured on aFinnigan GC-MS-4021 mass spectrometer. High resolutionmass spectrometry data were obtained on a Finnigan-Mat 8430high-resolution mass spectrometer. Extracts were dried overanhydrous sodium sulfate.

3-Bromo-1,1,1-trifluoroacetone 2

This was obtained from Aldrich Chemical Company.

Scheme 6

Ph3P + 6 [Ph3PBr]

CF3

CH[–CH2 OTi(O-i-Pr)3]

7 8

Scheme 7

C

O

C

H

P Br

CHCF3

C C

H

H CHCF3

C C

H

H CHCF3

OTi(O-i-Pr)3

OTi(O-i-Pr)3

R

R H

H

PhPhPh

9

10

3

8 + 7 + RCHO

OH

+ Ph3PO + HBr

R

Ethyl 2,2,2-trifluoroethyl ketone and butyl trifluoromethyl ketone

These were prepared according to the method reported.27

Ethyl pentafluoroethyl ketone and ethyl heptafluoropropyl ketone

These were prepared according to the method reported.28

Bromofluoro ketones

These were prepared according to the method reported.29

General procedure for the preparation of trifluoroalkylatedallylic alcohols 3

Into a mixture of 3-bromo-1,1,1-trifluoroacetone 2 (1 mmol),an aldehyde 1 (1 mmol) and triphenylphosphine (1 mmol) in acapped vessel under nitrogen was injected titanium() iso-propoxide (1 mmol). After having been stirred at 80 8C for 24 h,the reaction mixture was treated with 5% hydrochloric acid (10ml) and extracted with diethyl ether (3 × 20 ml). The organiclayer was washed with water (3 × 10 ml), dried and evaporatedto remove the solvent. The residue was chromatographed onsilica gel, and eluted with petroleum ether (60–90 8C)–ethylacetate (95 :5) to give the product. Yields are given in Table 1.

1,1,1-Trifluoro-4-phenylbut-3-en-2-ol 3a. Bp 114–115 8C/2.5mmHg. (Lit.,12a bp 76–77 8C/1 mmHg); νmax/cm21: 3390, 3060,1650, 1500, 1450, 1360, 1270, 1170, 1070, 1050 and 970;δH 7.44–7.28 (m, 5H), 6.86 (d, J 16.0, 1H), 6.20 (dd, J 16.0, 6.5,1H), 4.65–4.61 (m, 1H), 2.38 (br s, 1H); δF 1 1.4 (s); m/z 202(M1 57%), 133 (100), 115 (32), 113 (39), 105 (15), 103 (19), 91(18), 77 (23).

1,1,1-Trifluoro-4-(4-methylphenyl)but-3-en-2-ol (3b). Bp110 8C/2.5 mmHg; νmax/cm21: 3390, 1660, 1610, 1510, 1270,1170, 1130, 1040 and 970; δH 7.31 (d, J 8.1, 2H), 7.15 (d,J 8.1, 2H), 6.82 (d, J 16.0, 1H), 6.15 (dd, J 16.0, 6.7, 1H),4.63–4.59 (m, 1H), 2.35 (s, 3H), 2.25 (br s, 1H); δF 11.6 (s);m/z 216 (M1, 30), 147 (100), 129 (35), 117 (12), 115 (23), 105 (27),91 (27), 77 (11), 55 (50) [Found: C, 61.32; H, 5.02. C11H11F3O(216.20) requires C, 61.11; H, 5.13%].

1,1,1-Trifluoro-4-(4-fluorophenyl)but-3-en-2-ol (3c). Bp 102–104 8C/2.6 mmHg; νmax/cm21: 3400, 3040, 1660, 1600, 1510,1270, 1230, 1180, 1160 and 1130; δH 7.43–7.36 (m, 2H), 7.08–6.99 (m, 2H), 6.83 (d, J 16.0, 1H), 6.12 (dd, J 16.0, 6.4, 1H),4.66–4.60 (m, 1H), 2.43 (d, J 5.4, 1H); δF 11.4 (s, 3F), 135.0(s, 1F); m/z 221 (M1 1 1, 38), 220 (M1, 43), 151 (100), 133 (80),109 (72), 103 (52), 101 (53), 75 (47), 69 (46), 55 (77) [Found: C,54.25; H, 3.97. C10H8F4O (220.17) requires C, 54.55; H, 3.66%].

4-(4-Chlorophenyl)-1,1,1-trifluorobut-3-en-2-ol (3d). Bp112 8C/2.5 mmHg; νmax/cm21: 3580, 3430, 3050, 2980, 1650,1590, 1490, 1400, 1360, 1260, 1170, 1130, 1010 and 970; δH

7.37–7.30 (m, 4H), 6.82 (d, J 16.0, 1H), 6.17 (dd, J 16.0, 6.3,1H), 4.67–4.61 (m, 1H), 2.40 (d, J 5.8, 1H); δF 11.4 (s); m/z238 (M1 1 2, 17), 236 (M1, 52), 201 (12), 169 (34), 167 (100),149 (26), 132 (17), 103 (24) [Found: C, 50.86; H, 3.31. C10H8-ClF3O (236.62) requires C, 50.76; H, 3.41%].

1,1,1-Trifluoro-4-(4-methoxyphenyl)but-3-en-2-ol (3e). Bp120 8C/2 mmHg; νmax/cm21: 3500, 2930, 1600, 1580, 1500, 1260,1180, 1130 and 1030; δH 7.37–7.26 (m, 2H), 6.93–6.85 (m, 2H),6.78 (d, J 16.0, 1H), 6.05 (dd, J 16.0, 6.8, 1H), 4.65–4.55 (m,1H), 3.82 (s, 3H), 2.51 (s, 1H); δF 11.5 (s); m/z 232 (M1, 64),163 (100), 145 (30), 121 (30), 91 (24), 77 (17), 55 (48) [Found: C,57.00; H, 4.58. C11H11F3O2 (232.20) requires C, 56.90; H,4.77%].

1,1,1-Trifluoro-4-(4-nitrophenyl)but-3-en-2-ol (3f). Mp: 103–104 8C; νmax/cm21: 3400, 1600, 1510, 1340, 1270, 1170, 1130, 976

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1762 J. Chem. Soc., Perkin Trans. 1, 1999, 1759–1763

and 860; δH 8.23–8.19 (m, 2H), 7.59–7.55 (m, 2H), 6.97 (d, 1H,J 16.0), 6.38 (dd, J 16.0, 5.6, 1H), 4.90–4.60 (m, 1H), 2.88 (s,1H); δF 11.0 (s) m/z 247 (M1, 24), 178 (100), 132 (44), 103 (24),77 (19), 51 (14) [Found: C, 48.47; H, 3.21; N, 5.62. C10H8F3NO3

(247.17) requires C, 48.59; H, 3.26; N, 5.67%].

4-(3-Bromophenyl)-1,1,1-trifluorobut-3-en-2-ol (3g). Bp105 8C/2 mmHg; νmax/cm21: 3500, 1570, 1270, 1180, 1130 and970; δH 7.60–7.10 (m, 4H), 6.80 (d, J 16.0, 1H), 6.20 (dd,J 16.0, 6.3, 1H), 4.70–4.60 (m, 1H), 2.88 (s, 1H); δF 11.3 (s);m/z 282 (M1 1 2, 39), 280 (M1, 41), 213 (76), 211 (30), 132 (100),103 (37), 77 (31), 51 (24) [Found: C, 42.80; H, 3.12. C10H8BrF3O(281.07) requires C, 42.73; H, 2.87%].

4-(3-Chlorophenyl)-1,1,1-trifluorobut-3-en-2-ol (3h). Bp110 8C/2 mmHg; νmax/cm21: 3400, 1600, 1570, 1470, 1270, 1180,1130 and 970; δH 7.50–7.20 (m, 4H), 6.80 (dd, J 16.0, 0.8, 1H),6.20 (dd, J 16.0, 6.3, 1H), 4.70–4.55 (m, 1H), 2.75 (s, 1H);δF 11.3 (s); m/z 236 (M1, 72), 201 (23), 167 (100), 149 (39),132 (26), 103 (40), 77 (18), 69 (14), 55 (25) [Found: C, 50.27; H,3.60. C10H8ClF3O (236.62) requires C, 50.76; H, 3.41%].

4-(2-Bromophenyl)-1,1,1-trifluorobut-3-en-2-ol (3i). Bp 81 8C/2.5 mmHg; νmax/cm21: 3580, 3410, 1470, 1440, 1260, 1170, 1130,1020 and 970; δH 7.59–7.52 (m, 2H), 7.33–7.14 (m, 3H), 6.16(dd, J 15.9, 6.3, 1H), 4.72–4.67 (m, 1H), 2.41 (d, J 5.4, 1H);δF 11.4 (s); m/z 282 (M1 1 2, 24), 280 (M1, 24), 213 (30),211 (30), 201 (33), 133 (72), 131 (100), 102 (36), 77 (34), 69 (37),51 (20) [Found: C, 42.98; H, 2.72. C10H8BrF3O (281.07) requiresC, 42.73; H, 2.87%].

1,1,1-Trifluoro-6-phenylhexa-3,5-dien-2-ol (3j). Bp 118 8C/2.5mmHg; νmax/cm21: 3320, 3020, 1640, 1450, 1260, 1180, 1120,1040 and 990; δH 7.43–7.28 (m, 5H), 6.84–6.76 (m, 1H), 6.69–6.60 (m, 2H), 5.80 (dd, J 15.7, 6.6, 1H), 4.59–4.55 (m, 1H),2.24 (d, J 5.1, 1H); δF 11.7 (s); m/z 229 (M1 1 1, 13), 228 (M1,19), 159 (41), 141 (28), 130 (57), 129 (63), 115 (55), 102 (20), 92(70), 91 (100), 77 (18) [Found: C, 63.10; H, 4.59. C12H11F3O(228.21) requires C, 63.16; H, 4.86%].

4-(2,4-Dichlorophenyl)-1,1,1-trifluorobut-3-en-2-ol (3k). Bp110 8C/2 mmHg; νmax/cm21: 3500, 2900, 1470, 1260, 1180, 1110,1020 and 970; δH 7.50–7.00 (m, 4H), 6.20 (dd, J 16.0, 6.0, 1H),4.85–4.65 (m, 1H), 2.70 (s, 1H); δF 11.4 (s); m/z 270 (M1, 45),235 (12), 201 (100), 159 (52), 141 (44), 131 (25), 113 (33), 102(23), 77 (43) [Found: C, 43.99; H, 2.52. C10H7Cl2F3O (271.07)requires C, 44.31; H, 2.60%].

1,1,1-Trifluoro-4-piperonylbut-3-en-2-ol (3l). Bp 100 8C/2mmHg; νmax/cm21: 3430, 2950, 1600, 1500, 1490, 1450, 1250,1170 and 1130; δH 7.10–6.50 (m, 4H), 5.90 (s, 2H), 5.80(dd, J 15.9, 6.8, 1H), 4.59–4.42 (m, 1H), 2.53 (s, 1H); δF 11.5(s); m/z 246 (M1, 100), 177 (74), 147 (51), 135 (19), 119 (28),91 (33), 55 (13) [Found: M1, 246.0488. C11H9F3O3 requires M,246.0504].

General procedure for the preparation of substituted allylicalcohols 5

The procedure is similar with that of the preparation of com-pounds 3 and the reaction times and temperatures and yieldsare listed in Table 2.

1,1,1-Trifluoro-3-methyl-4-phenylbut-3-en-2-ol (5a). Bp 90 8C/1 mmHg; νmax/cm21 3390, 1500, 1450, 1270, 1170, 1130, 760 and700; δH 7.52–7.20 (m, 5H), 6.71 (s, 1H), 4.57 (q, J 7.0, 1H), 2.60(s, 1H), 2.00 (s, 3H); δF 20.7 (s); m/z 216 (M1, 62%), 147 (100),129 (86), 115 (32), 91 (44) [Found: C, 60.80; H, 5.09. C11H11F3O(216.20) requires C, 61.11; H, 5.13%]; NOESY spectrumshowed that the CH(OH)(CF3) group is cis (Z) with respect to4-H.

4-(3-Chlorophenyl)-1,1,1-trifluoro-3-methylbut-3-en-2-ol (5b).Bp 90 8C/1 mmHg; νmax/cm21 3420, 1600, 1570, 1480, 1270,1170 and 1120; δH 7.40–7.10 (m, 4H), 6.63 (s, 1H), 4.53 (q,J 7.0, 1H), 2.59 (s, 1H), 1.95 (s, 3H); δF 21.0 (s); m/z 250 (M1,59), 197 (13), 181 (100), 163 (50), 146 (32), 125 (31), 115 (52)[Found: C, 52.66; H, 4.13. C11H10ClF3O (250.65) requires C,52.71; H, 4.02%].

4-(3-Chlorophenyl)-1,1,1-trifluoro-3-propylbut-3-en-2-ol (5c).Bp 100 8C/1 mmHg; νmax/cm21: 3420, 1600, 1570, 1470, 1270,1170, 1130 and 780; δH 7.40–7.10 (m, 4H), 6.74 (s, 1H), 4.58 (q,J 6.5, 1H), 2.52–2.12 (m, 3H), 1.60–1.45 (m, 2H), 0.92 (t,J 7.5, 3H); δF 20.7 (s); m/z 278 (M1, 100), 261 (21), 225 (52),209 (63), 167 (39), 151 (33), 115 (77) [Found: C, 56.35; H, 5.22.C13H14ClF3O (278.70) requires C, 56.03; H,5.06%].

1,1,1-Trifluoro-4-(4-methoxyphenyl)-3-propylbut-3-en-2-ol(5d). Bp 90 8C/1 mmHg; νmax/cm21: 3460, 2960, 2880, 1610,1510, 1470, 1250, 1170 and 1130; δH 7.30–7.20 (m, 2H), 6.90–6.80 (m, 2H), 6.69 (s, 1H), 4.53 (q, J 7.0, 1H), 3.82 (s, 3H),2.60–2.20 (m, 3H), 1.60–1.40 (m, 2H), 0.94 (t, J 7.3, 3H);δF 20.8 (s); m/z 274 (M1, 100), 245 (63), 227 (28), 177(94), 205 (49), 146 (52) [Found: C, 61.08; H, 6.24. C14H17F3O2

(274.28) requires C, 61.31; H,6.25%].

1-(2-Bromophenyl)-4,4,5,5,5-pentafluoro-2-methylpent-1-en-3-ol (5e). Bp 80 8C/1 mmHg; νmax/cm21: 3440, 1560, 1470, 1440,1210, 119, 1130 and 1025; δH 7.65–7.10 (m, 4H), 6.70 (s, 1H),4.67–4.77 (m, 1H), 2.62 (d, J 3.8 1H), 1.87 (s, 3H); δF 4.5 (s,3F), 46.5 (d, J 8.8, 1F), 48.0 (d, J 14.0, 1F); m/z 344 (M1, 7),227 (51), 146 (100), 131 (37), 115 (48) [Found: C, 41.41; H, 2.73.C12H10BrF5O (345.11) requires C, 41.76; H, 2.92%].

4,4,5,5,5-Pentafluoro-1-(4-methoxyphenyl)-2-methylpent-1-en-3-ol (5f). Bp 85 8C/1 mmHg; νmax/cm21: 3460, 1610, 1580,1510, 1450, 1250, 1180 and 840; δH 7.30–7.20 (m, 2H), 6.95–6.85 (m, 2H), 6.57 (s, 1H), 4.60 (dd, J 9.4,15.8, 1H), 3.80 (s,3H), 2.82 (s, 1H), 1.95 (d, J 1.3, 3H); δF 4.5 (s, 3F), 46.5 (d,J 9.4, 1F), 47.7 (d, J 15.8, 1F); m/z 296 (M1, 49), 279 (9),177 (100), 159 (36), 121 (20) [Found: C, 52.95; H, 3.92. C13H13-F5O2 (296.24) requires C, 52.71; H, 4.42%].

1,1,1,2,2-Pentafluoro-4-methyl-7-phenylhepta-4,6-diene-3-ol(5g). Bp 120 8C/1 mmHg; νmax/cm21: 3440, 1490, 1450, 1210,1190, 1130, 970 and 750; δH 7.55–7.20 (m, 5H), 7.00 (dd,J 10.9, 15.6, 1H), 6.63 (d, J 15.6, 1H), 6.35 (d, J 10.9, 1H), 4.55(dd, J 8.6, 16.3, 1H), 2.84 (s, 1H), 1.95 (s, 3H); δF 4.5 (s, 3F),46.5 (d, J 8.6, 1F), 48.3 (d, J 16.3, 1F); m/z 292 (M1, 15), 276(21), 173 (41), 143 (41), 115 (48), 105 (57), 91 (76), 43 (100)[Found: C, 57.10; H, 4.00. C14H13F5O (292.25) requires C,57.54; H, 4.48%].

1-(2,4-Dichlorophenyl)-4,4,5,5,5-pentafluoro-2-methylpent-1-en-3-ol (5h). Bp 100 8C/1 mmHg; νmax/cm21: 3430, 1590, 1550,1470, 1210, 1190, 1130 and 820; δH 7.39 (d, J 2.0, 1H), 7.30–7.10 (m, 2H), 6.65 (s, 1H), 4.69 (dd, J 9.1, 15.7, 1H), 2.78 (s,1H), 1.83 (d, J 1.3, 3H); δF 4.3 (s, 3F), 46.3 (d, J 9.1, 1F),47.7 (d, J 15.7, 1F); m/z 334 (M1, 14), 215 (100), 197 (17), 180(36), 145 (27), 115 (44). [Found: C, 42.76; H, 2.45. C12H9Cl2F5O(335.10) requires C, 43.01; H, 2.71%].

4,4,5,5,6,6,6-Heptafluoro-2-methyl-1-phenylhex-1-en-3-ol(5i). Bp 65 8C/1 mmHg; νmax/cm21: 3410, 1490, 1450, 1230, 1120and 940; δH 7.45–7.20 (m, 5H), 6.68 (s, 1H), 4.73 (dd, J 8.0, 17.1,1H), 2.80 (s, 1H), 2.00 (d, J 0.66, 3H); δF 3.5 (t, 3F), 42.9–44.2(m, 1F), 44.9–46.2 (m, 1F), 49.0 (s, 2F); m/z 316 (M1, 7), 234(18), 219 (46), 181 (47), 147 (100), 129 (50), 43 (31) [Found: C,49.66; H, 3.52. C13H11F7O (316.22) requires C, 49.38; H,3.51%]. NOESY spectrum showed that the CH(OH)(C3F7)group is cis (Z) with respect to 1-H.

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J. Chem. Soc., Perkin Trans. 1, 1999, 1759–1763 1763

4,4,5,5,6,6,6-Heptafluoro-1-(4-fluorophenyl)-2-methylhex-1-en-3-ol (5j). Bp 54 8C/ 1 mmHg; νmax/cm21: 3420, 1600, 1510,1450, 1230, 1190, 1120 and 740; δH 7.40–7.15 (m, 2H), 7.10–6.95 (m, 2H), 6.62 (s, 1H), 4.70 (dd, J 7.8, 17.0, 1H), 2.75 (s,1H), 1.95 (s, 3H); δF 3.6 (s, 3F), 37.0 (s, 1F), 42.9–44.2 (m, 1F),45.1–46.4 (m, 1F), 48.0 (s, 2F); m/z 165 (100), 147 (34), 109 (15)[Found: C, 46.65; H, 3.00. C13H10F8O (334.21) requires C,46.72; H, 3.02%].

1-(2-Bromophenyl)-4,4,5,5,6,6,6-heptafluoro-2-methylhex-1-en-3-ol (5k). Bp 70 8C/1 mmHg; νmax/cm21: 3450, 1560, 1470,1440, 1225, 1180, 1115 and 750; δH 7.60–7.55 (d, J 8.0, 1H),7.40–7.20 (m, 2H), 7.15–7.05 (m, 1H), 6.69 (s, 1H), 4.78 (dd,J 7.6, 17.3, 1H), 2.72 (s, 1H), 1.86 (d, J 0.66, 3H); δF 3.5 (s,3F), 42.9–44.2 (m, 1F), 45.1–46.4 (m, 1F), 48.0 (s, 2F); m/z195 (0.65), 146 (100), 131 (33), 115 (36) [Found: C, 39.54; H, 2.59.C13H10BrF7O (395.11) requires C, 39.52; H, 2.55%].

4,4,5,5,6,6,6-Heptafluoro-1-(4-methoxyphenyl)-2-methylhex-1-en-3-ol (5l). Bp 80 8C/1 mmHg; νmax/cm21: 3460, 1610, 1580,1510, 1225, 1180, 1110 and 740; δH 7.35–7.15 (m, 2H), 6.90–6.80 (m, 2H), 6.56 (s, 1H), 4.68 (dd, J 7.8, 17.1, 1H), 3.80 (s,3H), 3.02 (s, 1H) 1.96 (d, J 1.0, 3H); δF 3.5 (t, 3F), 42.9–44.2(m, 1F), 45.1–46.4 (m, 1F), 48.5 (s, 2F); m/z 177 (100), 159 (33),121 (19), 69 (12) [Found: C, 48.52; H, 3.85. C14H13F7O2 (346.24)requires C, 48.57; H, 3.78%].

AcknowledgementsWe thank the National Natural Science Foundation of China,the Laboratory of Organometallic Chemistry and AcademiaSinica for financial support.

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which was sensitive to moisture. Bp 110 8C/0.1 mmHg; δH(300 MHz;CDCl3; TMS) 5.00–4.20 (m, 4H), 3.58 [dd, 2J(H,H) 10.9, 3J(H,H),3.2, 1H], 3.10 [dd, 2J(H,H) 10.6, 3J(H,H) 8.8, 1H], 1.28 [d, 3J(H,H)6.1, 18H]; δF(60 MHz; CDCl3; TFA) 0.3 [d, 3J(H,F) 5.4].

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